Field of the Invention
The present invention relates to a fundus inspection apparatus used for photographing a surface image and a tomographic image of a fundus of an eye to be inspected.
Description of the Related Art
Recently, there has been put to practical use a device (hereinafter also referred to as an OCT device) using an optical coherence tomography (OCT) in which a tomographic image is photographed by utilizing interference due to low coherence light. In this device, since the tomographic image can be photographed with about the same resolution as the wavelength of light entering an object to be inspected, the tomographic image of the object to be inspected can be obtained with a high resolution. The OCT device is particularly useful as an ophthalmic device for obtaining a tomographic image of a retina in a fundus.
Meanwhile, in an ophthalmic device at large, regardless of inspection of a fundus, it is important to highly accurately align an inspection portion (mainly, measurement optical system) of the device with respect to an eye to be inspected for photographing.
Japanese Patent Application Laid-Open No. 2000-245698 discloses an eye refractive power measurement apparatus which, when the eye is opacified due to cataract, for example, drives a measurement portion with respect to the eye to be inspected to receive, at each measurement position, light returned from a fundus by a sensor, and, thus, to predict whether measurement can be performed well based on the amount of the received light, whereby the measurement is performed at a good position.
Japanese Patent Application Laid-Open No. 2010-181172 discloses an optical image measurement device which is an OCT device automatically photographing a tomographic image when alignment is in a good state.
When the device disclosed in the Japanese Patent Application Laid-Open No. 2000-245698 is applied to the OCT device, the inspection time is relatively long because of various scanning operations. Therefore, when involuntary eye movement continuously occurs, an optimum position is required to be automatically found at every involuntary eye movement, so that there is a problem that the alignment time is increased.
In the Japanese Patent Application Laid-Open No. 2010-181172, although an automatic alignment of the eye to be inspected is described, a specific configuration is not described.
Thus, in the OCT device in which the inspection time per subject is relatively long, continuous automatic alignment is desired.
In many cases, the alignment with respect to the eye to be inspected is performed, regardless of manually or automatically, by detecting a pupil center position of an anterior eye portion and aligning an optical axis of a measurement portion with respect to the pupil center position. However, in such case, a tomographic image of a fundus may be darkened according to the eye to be inspected. In such case, in a manual OCT device, it is necessary that an operator perform fine adjustment to improve the tomographic image of the fundus.
In this regard, there is no OCT device which continuously performs automatic alignment, nor is there OCT device in which good images are continuously obtained.